1. Field of the Invention
This invention relates to an imaging apparatus which performs a ranging calculation by use of a phase difference pixel output, an imaging method, and a storage medium.
2. Description of the Related Art
There has been known a technique to perform a ranging calculation by use of a phase difference pixel output of phase difference pixels arranged on an imaging surface, and detect a focus on the basis of the result of the ranging calculation. In the ranging calculation, ranging performance deteriorates due to the increase of a calculation error when the phase difference pixel output is smaller than a sensor output range. It is therefore necessary to ensure a predetermined phase difference pixel output.
However, in general, the phase difference pixel output is about half or less than a recording pixel output used for display or recording. Thus, various methods to ensure that the phase difference pixel output may be substantially equal to the recording pixel output have been suggested.
For example, according to Japanese Patent No. 5319347, storage control of a charge in an imaging row used for pixel generation and storage control of a charge in a focus detection row having phase difference pixels are independently performed in one frame.
According to Japanese Patent No. 5565105, additional focus detection data is calculated by performing addition processing to add at least one focus detection data to the latest focus detection data included in the latest pixel data among pixel data generated by an image pickup device.